Abstract:

Provided is an optical path change member including a holding member body
formed of a transparent material. The holding member body includes: at
least two rows of optical-fiber insertion holes which hold optical fibers
inserted therein, such that the optical axes of the optical fibers are
inclined with respect to an optical axis of the optical device, and a
reflective inner surface which totally internally reflects light incident
from the optical-fiber insertion holes to a surface of the holding member
body configured to face an optical device on a board.

Claims:

1. An optical path change member comprising:a holding member body formed
of a transparent material, the holding member body comprising:at least
two rows of optical-fiber insertion holes which hold optical fibers
inserted therein, such that the optical axes of the optical fibers are
inclined with respect to an optical axis of the optical device, anda
reflective inner surface which totally internally reflects light incident
from the optical-fiber insertion holes to a surface of the holding member
body configured to face an optical device on a board.

2. The optical path change member according to claim 1,wherein the holding
member body further comprises an array of first lenses formed on the
reflective inner surface, wherein each of the first lenses is concave
when viewed from an incident direction of light and is aligned with one
of the optical-fiber insertion holes.

3. The optical path change member according to claim 1,wherein positions
of the optical-fiber insertion holes in the optical-fiber insertion hole
arrays are shifted from each other between adjacent rows.

4. The optical path change member according to claim 2,wherein second
lenses are provided between the reflective surface and the light input
and output ends, and at least two lenses are provided on an optical path
between the multi-core optical fiber and the light input and output end.

5. The optical path change member according to claim 1, wherein the
holding member body further comprises a positioning convex portion which
protrudes therefrom.

6. The optical path change member according to claim 5,wherein, the
positioning convex portion is a positioning pin.

7. The optical path change member according to claim 6,wherein the
positioning pin protrudes from the surface of the holding member body
configured to face an optical device and is integrally molded with the
holding member body.

8. A holding member body for an optical path change member, the holding
member body comprising:at least two rows of optical-fiber insertion holes
which hold optical fibers inserted therein, a reflective inner surface
which totally internally reflects light incident from the optical-fiber
insertion holes to a surface of the holding member body configured to
face an optical device on a board.

9. The holding member body according to claim 8,wherein the holding member
body further comprises an array of first lenses formed on the reflective
inner surface, wherein each of the first lenses is concave when viewed
from an incident direction, of light and is aligned with one of the
optical-fiber insertion holes.

10. The holding member body for an optical path change member according to
claim 8,wherein positions of the optical-fiber insertion holes in the
optical-fiber insertion hole arrays are shifted from each other between
adjacent rows.

11. The holding member body according to claim 8, further comprising a
positioning convex portion which protrudes therefrom.

12. The holding member body for an optical path change member according to
claim 11,wherein the positioning convex portion is a positioning pin.

13. The holding member body for an optical path change member according to
claim 12,wherein the positioning pin protrudes from the surface of the
holding member body configured to face an optical device and is
integrally molded with the holding member body.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to an optical path change member
provided at a terminal of a light transmission medium such as an optical
fiber, and a holding member body used for the optical path change member.
The optical path change member is an optical part for, changing an
optical path direction between an optical fiber and a light input and
output end provided on a board to optically connect the optical fiber
with the light input and output end.

[0003]Priority is claimed on Japanese Patent Application No. 2009-210376
filed on. Sep. 11, 2009, the disclosure of which is incorporated herein
by reference.

[0004]2. Description of the Related Art

[0005]In recent years, a scheme of fixing an optical connector assembled
with a front end portion of an optical fiber arranged along aboard, on
the board to be optically connected to an optical device mounted on the
board, such as a light-emitting device such as a vertical cavity surface
emitting laser (hereinafter, referred to as a VCSEL) or a light-receiving
device such as a photodiode (PD), from or to which light is output or
input vertically to the board, has been widely used.

[0006]A structure for changing an optical path to optically connect the
optical fiber with the optical device is provided in such an optical
connector. As a representative optical connector having this structure, a
photonic turn, optical connector (a PT optical connector) for changing an
optical axis by 90° inside the connector (standardized in
JPCA-PE03-01-06S) is available.

[0007]The PT optical connector is a board-mounted optical connector for
optically connecting a multi-core optical fiber, such as a multi-core
optical fiber ribbon, with an optical device on a flexible wiring board.
The PT optical connector has begun to be used for optical interconnection
of a router, a server, a parallel computer and the like.

[0008]An optical path change member for changing an optical path direction
of a multi-core optical fiber is disclosed in Japanese Unexamined Patent
Application, First Publication No. 2006-184782. The optical path change
member changes an optical path of two-dimensionally arranged multi-core
optical fibers. In the optical path change member, the multi-core optical
fibers in an upper row are inclined with respect to the multi-core
optical fibers in a lower row, and front ends of the optical fibers in
the upper and lower rows are closer. This prevents a great optical path
difference. The optical path change member is of an outer-surface
reflection type in which light output from the optical fiber or an
optical device collides with a reflective surface from the outside of an
optical path change member body.

[0009]An optical module is used as the optical device connected with the
multi-core optical fiber. This optical module is an optical part
including a multi-channel light-emitting device, a multi-channel
light-receiving device, and a transmitting and receiving circuit.

[0010]An inner-surface reflection type of a PT optical connector in which
light from the inside of an optical path change member body collides with
a reflective surface through the inside of the optical path change member
body is disclosed as an optical path change member in Japanese Unexamined
Patent Application, First Publication No 2007-121973. A lens is formed on
a lower surface of the optical path change member. Light output from a
front end of an optical fiber is totally reflected toward a circuit board
by the reflective surface, focused by the lens, and optically connected
with a light input and output end of the circuit board. When the optical
device of the circuit board is a light-emitting device, light output from
the light-emitting device is focused by the lens, totally reflected by
the reflective surface, and optically connected with the front end of the
optical fiber.

[0011]A PT optical connector in which multi-core optical fibers are
two-dimensionally arranged is disclosed in Japanese Unexamined Patent
Application, First Publication No. 2006-184680. In the optical path
change member, the optical fiber hole arrays corresponding to the
multi-core optical fibers are shifted from each other. As the optical
fiber hole arrays are arranged to be shifted from each other, light
interference can be prevented.

[0012]However, the reflective surface in the conventional optical path
change member is an inclined flat surface. Accordingly, it is difficult
to change an optical path of incident light in an optimal direction. If
the reflective surface is the flat inclined surface, optical connection
may not be maintained when the direction of the incident light is
shifted. In particular, if the multi-core optical fibers are
two-dimensionally arranged, it is difficult to position the multi-core
optical fiber and the optical device with respect to each other.

[0013]The present invention has been achieved in view of the above
circumstances, and it is an object of the present invention to provide an
optical path change member for allowing an optical path to be accurately
changed on a reflective surface even when multi-core optical fibers are
two-dimensionally arranged, and a holding member body used for the
optical path change member.

SUMMARY OF THE INVENTION

[0014]In order to achieve the object, the invention has employed the
followings.

[0015](1) An optical path change member according to an aspect of the
present invention includes: a holding member body formed of a transparent
material, the holding member body includes: at least two rows of
optical-fiber insertion holes which hold optical fibers inserted therein,
such that the optical axes of the optical fibers are inclined with
respect to an optical axis of the optical device, and a reflective inner
surface which totally internally reflects light incident from the
optical-fiber insertion holes to a surface of the holding member body
configured to face an optical device on a board.

[0016]According to the optical path change member described in (1), the
optical path is accurately changed on the reflective surface even when
the multi-core optical fibers are two-dimensionally arranged.

[0017](2) It is may be arranged such that in the optical path change
member described in (1), the holding member body further includes an
array of first lenses formed on the reflective inner surface, wherein
each of the first lenses is concave when viewed from an incident
direction of light and is aligned with one of the optical-fiber insertion
holes.

[0018]In the case of (2), light incident to the reflective surface can be
focused by the first lenses in the concave shape. Accordingly, the
optical path direction can be accurately changed

[0019](3) It may be arranged such that in the optical path change member
described in (1) or (2), positions of the optical-fiber insertion holes
in the optical-fiber insertion hole arrays are shifted from each other
between adjacent rows.

[0020]In the case of (3), an interval between the end faces of the optical
fibers positioned by the optical-fiber insertion holes is broadened and
interference of noise or signal light due to beam spread to the optical
paths of the adjacent optical fibers is prevented, thus realizing an
excellent optical connection.

[0021](4) It may be arranged such that in the optical path change member
described in any one of (1) to (3), second lenses are provided between
the reflective surface and the light input and output ends, and at least
two lenses are provided on an optical path between the multi-core optical
fiber and the light input and output end.

[0022]In the case of (4), even when the direction of the incident light
between the reflective surface and the light input and output end is
shifted, the optical path can be maintained in a desired direction by the
second lenses.

[0023](5) It may be arranged such that in the optical path change member
described in any one of (1) to (4), the holding member body further
includes a positioning convex portion which protrudes therefrom.

[0024]In the case of (5), the multi-core optical fiber arranged to face
the reflective surface is correctly positioned with respect to the light
input and output ends.

[0025](6) It may be arranged such that in the optical path change member
described in (5), the positioning convex portion is a positioning pin.

[0026](7) It may be arranged such that in the optical path change member
described in (6), the positioning pin protrudes from the surface of the
holding member body configured to face an optical device and is
integrally molded with the holding member body.

[0027](8) A holding member body for an optical path change member
according to another aspect of the present invention is a holding member
body for an optical path change member, the holding member body
including: at least two rows of optical-fiber insertion holes which hold
optical fibers inserted therein, a reflective inner surface which totally
internally reflects light incident from the optical-fiber insertion holes
to a surface of, the holding member body configured to face an optical
device on a board.

[0028](9) It may be arranged such that in the holding member body for an
optical path change member described in (8), the holding member body
further includes an array of first lenses formed on the reflective inner
surface, wherein each of the first lenses is concave when viewed from an
incident direction of light and is aligned with one of the optical-fiber
insertion holes.

[0029](10) It may be arranged such that in the holding member body for an
optical path change member described in (8) or (9), positions of the
optical-fiber insertion holes in the optical-fiber insertion hole arrays
are shifted from each other between adjacent rows.

[0030](11) It may be arranged such that in the holding member body for an
optical path change member described in any one of (8) to (10), the
holding member further includes a positioning convex portion which
protrudes therefrom.

[0031](12) It may be arranged such that in the holding member body for an
optical path change member described in (11), the positioning convex
portion is a positioning pin.

[0032](13) It may be arranged such that in the holding member body for an
optical path change member described in (12), the positioning pin
protrudes from the surface of the holding member body configured to face
an optical device and is integrally molded with the holding member body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a cross-sectional view of an optical path change member
according to a first embodiment of the present invention.

[0034]FIG. 2 is a cross-sectional view of a holding member body
constituting the optical path change member.

[0035]FIG. 3 is a cross-sectional view of the holding member body taken
along a line III-III in FIG. 2.

[0036]FIG. 4 is a cross-sectional view of the holding member body taken
along a line IV-IV in FIG. 2.

[0037]FIG. 5 is a cross-sectional view of a holding member body taken
along a line IV-IV according to a second embodiment of the present
invention.

[0038]FIG. 6 is a schematic view showing attachment of the holding member
body to an optical module.

[0039]FIG. 7 is a cross-sectional view of an optical path change member
according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

[0040]Hereinafter, a first embodiment of the present invention will be
described in detail with reference to the accompanying drawings.

[0041]FIG. 1 is a cross-sectional view of an optical path change member 1
according to the first embodiment of the present invention. As shown in
FIG. 1, a holding member body 2 provided at terminals of multi-core
optical fibers 6 arranged in two rows is attached to an optical module 3
(board) having a light-emitting device 42 and a light-receiving device 43
mounted thereon. FIG. 2 is a cross-sectional view showing the holding
member body 2 constituting the optical path change member 1 according to
the first embodiment of the present invention. FIG. 3 is a
cross-sectional view of the holding member body 2 taken along a line
III-III in FIG. 2. FIG. 4 is a cross-sectional view of the holding member
body 2 taken along a line IV-IV in FIG. 2. In FIG. 4, an arrangement of
first lenses 22 formed on a reflective surface 21 provided in the optical
path change member 1 is shown. FIG. 5 is a cross-sectional view of a
holding member body taken along a line IV-IV according to a second
embodiment of the present invention. FIG. 6 is a schematic view showing
an attachment of the holding member body 2 to the optical module 3.

[0042]Hereinafter, a front end direction of the multi-core optical fiber 6
(a left direction in FIG. 1) may also be referred to as a front side and
a reverse direction (a right direction in FIG. 1) may also be referred to
as a rear side. A longitudinal direction is an optical axis direction of
the multi-core optical fiber 6.

[0043]As shown in FIG. 1, the holding member body 2 includes the optical
path change member 1 and is provided at the terminals of the multi-core
optical fibers 6. The holding member body 2 is attached to the optical
module 3 assembled on a circuit board 7, such that the light input and
output end 41 of a light-emitting device 42 and a light-receiving device
43 are optically connected with the multi-core optical fibers 6. First
lenses 22 for focusing light are formed on the reflective surface 21.

[0044]In general, the multi-core optical fiber 6 is called a multi-core
optical fiber ribbon. The multi-core optical fiber 6 is a set of a
plurality of optical fibers 61 collected by a tape coating (a second
coating). In the present embodiment, the multi-core optical fibers 6 are
arranged in two rows. A cylindrical boot 64 of, for example, flexible
rubber is attached on the periphery of the multi-core optical fibers 6
arranged in the two rows. The boot 64 collectively holds the multi-core
optical fibers 6 configured in the two rows. Accordingly, the multi-core
optical fibers 6 are prevented from scattering. The boot 64 performs a
function of protecting the multi-core optical fibers 6 so that the
multi-core optical fibers 6 are not subjected to sharp bending that
affects an optical transmission characteristic.

[0045]The multi-core optical fiber 6 is not limited to a multi-core
optical fiber ribbon. For example, various structures such as a plurality
of single-core optical fibers may be employed.

[0046]Next, the optical module 3 will be described.

[0047]The optical module 3 is assembled on the circuit board 7. The
optical module 3 has a function of driving the light-emitting device 42
(a light input and output end 41) based on a control signal from a
driving circuit on the circuit board 7, or a function of delivering an
electrical signal corresponding to a light signal received by the
light-receiving device 43 (the light input and output end 41) to a
processing circuit on the circuit board 7. Alternatively, the optical
module 3 has both of the above-described functions.

[0048]The optical module 3 includes an optical module body 4 having the
light input and output end 41 mounted thereon (or embedded therein), and
a lens holder 5. The lens holder 5 is mounted on an upper surface of the
optical module body 4 which is directly disposed on the circuit board 7.
The lens holder 5 has the same shape as the optical module body 4 when
viewed from the top. In the example shown, the optical module 3 is formed
in a block shape. The upper surface of the optical module 3 is a bonding
surface 31 on which the holding member body 2 is mounted.

[0049]The optical module body 4 constituting a lower portion of the
optical module 3 is a member in a block shape directly attached to the
circuit board 7. The optical module body 4 includes an upper surface 45
connected with the lens holder 5 and a lower surface 46 connected with
the circuit board 7.

[0050]A first concave portion 44 is formed on the upper surface 45 of the
optical module. The light input and output end 41 of the light-emitting
device 42 and the light-receiving device 43 is mounted in the first
concave portion 44. The light input and output ends 41 are provided in a
plurality of rows in a lateral direction of the optical module 3 to
correspond to the arrangement of the optical fibers 61 constituting the
multi-core optical fibers 6. The arrangement of the light input and
output ends 41 depends on the arrangement of the multi-core optical
fibers 6 and the first lenses 22, and the arrangement will be described
later.

[0051]The light input and output end 41 includes the light-emitting device
such as a VCSEL or the light-receiving device such as a photodiode (PD).
In the present embodiment, for example, among the light input and output
ends 41 provided in two rows in the longitudinal direction, the
light-emitting devices 42 are provided in a row at a front side and the
light-receiving devices 43 are provided in a row at a rear side.

[0052]An optical axis direction of the light input and output end 41 of
the optical module body 4 is substantially vertical to the circuit board
7 (see FIG. 1). The optical axis direction of the light input and output
end 41 may be inclined at an angle other than 90° with respect to
the circuit board 7.

[0053]The lens holder 5 having substantially the same shape as the optical
module body 4 when viewed from the top is provided on the upper surface
45 of the optical module body 4. The lens holder 5 is formed integrally
with the optical module body 4 using a given method. The lens holder 5 is
formed of a transparent material. Second lenses 33 are formed on an upper
surface of the lens holder 5 using integral molding. The second lens 33
is a spherical or aspherical convex lens that is convex upward. Examples
of a preferred material of the lens holder 5 include polycarbonate (PC),
ZEONEX (amorphous cycloolefin polymer: registered trademark),
ULTEMNATURAL (polyetherimide: registered trademark), polymethyl
methacrylate (PMMA), modified polyolefin, polyphenylsulfone (PPSU), and
epoxy resin.

[0054]The second lens 33 is formed in a second concave portion 34 provided
on the upper surface 53 of the lens holder 5 not to interfere with the
optical path change member 1 when the optical path change member 1 is
attached. The second lenses 33 are provided in a plurality of rows to
correspond to the arrangement of the optical fibers 61 constituting the
multi-core optical fibers 6, similar to the light input and output ends
41. The second lenses 33 are disposed on extensions of the optical axes
of the light input and output ends 41. This arrangement will be described
later.

[0055]The guide portion 52 is formed at the front of the lens holder 5 and
functions as an alignment member when the holding member body 2 is
attached to the optical module 3. At a front portion of the lens holder
5, the guide portion 52 is fanned in a vertical direction, and the lens
holder base portion 51 and the guide portion 52 are integrally formed in
an L-figured shape.

[0056]A photoelectric conversion circuit, a control processing unit, an
optical signal processing circuit, an optical device driving circuit, and
various circuits for driving and controlling electronic parts on the
circuit board are provided on the circuit board 7 having the optical
module 3 mounted thereon, although not shown.

[0057]Next, the holding member body 2 will be described.

[0058]The holding member body 2 is assembled to cover the front ends of
the multi-core optical fibers 6. The holding member body 2 optically
connects the multi-core optical fibers 6 with the light input and output
ends 41. As described above, the optical axes of the multi-core optical
fibers 6 are inclined with respect to the optical axes of the light input
and output end 41. Accordingly, an optical path is changed by the
reflective surface 21 in the holding member body 2, such that the optical
connection is performed.

[0059]The holding member body 2 is formed of a transparent material, and
is a member in a block shape having the reflective surface 21 and the
optical-fiber insertion holes 24 formed therein. Examples of a preferred
material of the holding member body 2 include polycarbonate (PC), ZEONEX
(amorphous cycloolefin polymer: registered trademark), ULTEMNATURAL
(polyetherimide: registered trademark), PMMA, modified polyolefin, PPSU,
and epoxy resin

[0060]A reflective-surface-formed concave portion 23 is formed on the
upper surface of the holding member body 2. The reflective-surface-formed
concave portion 23 has a groove shape extending in a lateral direction of
the holding member body 2. The reflective-surface-formed concave portion
23 has a cross-section in the shape of a trapezoid of which the width is
gradually reduced in a depth direction.

[0061]Among inner surfaces of the reflective-surface-formed concave
portion 23, a rear surface 23a (at the multi-core optical fiber 6 side)
is an inclined surface. This inclined surface is the reflective surface
21. The reflective surface 21 is positioned on extensions of the optical
axes of the multi-core optical fibers 6, and is located above the light
input and output ends 41 when the holding member body 2 is fixed on the
optical module 3.

[0062]The reflective surface 21 is formed to be inclined with respect to
the optical axis direction of the multi-core optical fiber 6 (a
horizontal direction in FIG. 1) and the optical axis direction of the
light input and output end 41 (a vertical direction in FIG. 1). The
reflective surface 21 inner-surface-reflects, inside the holding member
body 2, light from the multi-core optical fiber 6 incident to the holding
member body 2, toward the light input and output end 41. Alternatively,
the reflective surface 21 inner-surface-reflects, inside the holding
portion body 2, light from the light input and output end 41 incident to
the holding member body 2, toward the front end of the multi-core optical
fiber 6.

[0063]The reflective surface 21 optically connects the multi-core optical
fiber 6 with the light input and output end 41 by the
inner-surface-reflection inside the holding member body 2. This
inner-surface-reflection is based on a refractive index difference
between the material of the holding member body 2 and air (the
reflective-surface-formed concave portion 23). A higher efficiency of the
reflection on the reflective surface 21 is preferable. The
reflective-surface-formed concave portion 23 may be applied with another
gas and sealed, as long as an appropriate refractive index difference
between the gas in the reflective-surface-formed concave portion 23 and
the material of the holding member body 2 is satisfied.

[0064]The first lenses 22 corresponding in number to the optical fibers 61
constituting the multi-core optical fiber 6 are formed on the reflective
surface 21. The first lens 22 is a spherical lens or aspherical lens
having a concave shape when viewed from the multi-core optical fiber and
the light input and output end 41 (in other words, when viewed from an
incident direction of light). A curvature of the first lens 22 is
designed so that the end face of the optical fiber 61 is positioned at a
focusing point of the reflected light. The first lens 22 is formed so
that a center of the first lens 22 is positioned on the reflective
surface 21 and on an extension of the optical axis of the optical fiber
61 and an extension of the optical axis of the light input and output end
41. Accordingly, the arrangement of the first lenses 22 depends on the
arrangement of the optical fibers 61. The arrangement of the optical
fibers 61 (the multi-core optical fibers 6) will be described later.

[0065]The multi-core optical-fiber insertion hole 24 is formed in a
longitudinal direction in a rear portion of the holding member body 2.
The multi-core optical-fiber insertion hole 24 has a rear end opened at a
rear surface 2a of the holding member body 2.

[0066]The multi-core optical-fiber insertion hole 24 is subjected to a
termination process, and has such a shape that the multi-core optical
fibers 6 jacketed with a boot 64 can be tightly held. Specifically, the
multi-core optical-fiber insertion hole 24 includes optical-fiber
insertion holes 25 into which the optical fibers 61 of the multi-core
optical fibers 6 are inserted, a multi-core optical fiber holding portion
26 corresponding to an outer diameter of the tape coating covering the
optical fiber 61, and a boot insertion portion 27 corresponding to the
boot 64 holding the multi-core optical fibers 6. The optical fiber
insertion portions 25 are formed to correspond in number to the optical
fibers 61.

[0067]A first tapered portion 26a serving as a guide when the optical
fiber 61 is inserted into the optical-fiber insertion hole 25 is formed
between the optical-fiber insertion hole 25 and the multi-core optical
fiber holding portion 26. Similarly, a second tapered portion 27a is
formed between the multi-core optical fiber holding portion 26 and the
boot insertion portion 27.

[0068]The optical-fiber insertion hole 25 is machined to a depth for
positioning the front end of the optical fiber 6 and the first lens 22 to
a predefined position. In other words, each optical-fiber insertion hole
25 is formed so that the front end of the optical fiber 61 is consistent
with a focusing point of the first lens 22 when the multi-core optical
fiber 6 is inserted so that the front end of the optical fiber 61
contacts a bottom portion 25c of the optical-fiber insertion hole 25.

[0069]A housing (not shown) for preventing light from entering the holding
member body 2 may be provided around the holding member body 2.

[0070]As shown in FIGS. 2 to 6, the holding member body 2 includes two
positioning pins 29 (positioning convex portions) protruded from the
mounting surface 28. The positioning pins 29 are disposed substantially
at a center in the longitudinal direction of the holding member body 2
not to interfere with the optical path. The positioning pin 29 has a
cylindrical shape. The positioning pins 29 are formed integrally with the
holding member body 2 using integral molding, and has a tapered portion
29a provided at a front end thereof.

[0071]As shown in FIG. 6, positioning pin holes 39 (positioning concave
portions) are formed on the bonding surface 31 of the optical module 3
contacting the holding member body 2. Each positioning pin hole 39 has a
shape designed to correspond to the shape of the positioning pin 29 so
that the positioning pin 29 is accurately positioned. In the present
embodiment, the positioning pin hole 39 is a round hole into which the
positioning pin 29 formed as a round bar is fitted.

[0072]The present invention is not particularly limited to this example,
and the positioning pin 29 may be provided as a separate member, instead
of being integrally molded with the holding member body 2. For example, a
mounting hole may be provided in the holding member body 2 and a round
bar pin of stainless steel may be inserted into the mounting hole.
Alternatively, a positioning pin may protrude from the optical module 3,
a positioning pin hole may be formed in the holding member body 2, and
the positioning pin may be fitted into the positioning pin hole.

[0073]The number of the positioning pins 29 is not particularly limited,
but the number may be 1, 2, 3 or greater depending on, for example,
purposes. The shapes of the positioning pin 29 and the positioning pin
hole 39 are not particularly limited. The positioning pin 29 and the
positioning pin hole 39 may have any shape, including an oval and a
square, depending on, for example, purposes.

[0074]As shown in FIGS. 3 and 4, the optical-fiber insertion holes 25 and
the first lenses 22 are arranged two-dimensionally to form a plurality of
rows. In the case of the optical-fiber insertion holes 25, a plurality of
rows 25A and 25B in which a plurality of optical-fiber insertion holes 25
are arranged side by side are disposed in a thickness direction of the
holding member body 2. Similarly, in the case of the first lenses 22, a
plurality of rows 22A and 22B in which a plurality of first lenses 22 are
arranged in the lateral direction of the holding portion body 2 are
disposed in the thickness direction of the holding member body 2.

[0075]In the holding member body 2 of the first embodiment, the
optical-fiber insertion holes 25 and the first lenses 22 are arranged in
the two rows to correspond to the multi-core optical fibers 6 configured
in two rows, as shown in FIGS. 3 and 4. For convenience, in the following
description of the holding member body 2 of the first embodiment, the
rows 25A, 25B, 22A and 22B are indicated as first rows 25A and 22A (at a
lower side in FIGS. 3 and 4) and second rows 25B and 22B (at an upper
side in FIGS. 3 and 4) in order of a smaller distance from the mounting
surface 28.

[0076]Next, detailed arrangements of the optical-fiber insertion holes 25
and the first lenses 22 will be described. The optical-fiber insertion
holes 25 and the first lenses 22 are at the same position when viewed
from the optical axis direction. Accordingly, the arrangement will be
described herein with reference to the positions of the optical-fiber
insertion holes 25.

[0077]As shown in FIG. 3, the optical-fiber insertion holes 25 are
arranged in the two rows 25A and 25B. In each row 25A or 25B, a plurality
of optical-fiber insertion holes 25 are laterally arranged and are
arranged at regular intervals of pitches p. Accordingly, a plurality of
optical fibers 61 of each multi-core optical, fiber 6 can be collectively
inserted and assembled into the holding member body 2. It is preferable
that the pitch p between the centers of the optical-fiber insertion,
holes 25 belonging to the same row 25A or 25B and adjacent to each other
corresponds to a pitch of the optical fiber 61 in the ribbon.
Accordingly, the respective optical fibers 61 can be aligned in parallel
and disadvantages such as loss increase due to bending of the optical
fibers 61 can be suppressed.

[0078]Further, the positions of the optical-fiber insertion holes 25 are
shifted from each other in the lateral direction of the holding member
body 2 (a horizontal direction in FIG. 3) between the first rows 25A and
the second rows 25B.

[0079]Here, a size d (d1, d2) of the shift of the optical-fiber insertion
holes 25 secured between the first row 25A and the second row 25B is
greater than a beam diameter of the optical path so that the optical
paths do not overlap. Since the beam diameter of the optical path is
slightly greater than a core diameter of the optical fiber 61 in
consideration of beam spread, the shift amount d (d1, d2) is set to a
value slightly greater than the core diameter. As long as this condition
is satisfied, the shift amount d1 between the optical-fiber insertion
hole 25a1 of the first row 25A and the optical-fiber insertion hole
25b of the second row 25B may be equal to or different from the shift
amount d2 between the optical-fiber insertion hole 25b of the second row
25B and the optical-fiber insertion hole 25a2 of the first row 25A.

[0080]As described above, the optical-fiber insertion holes 25 and the
first lenses 22 are at the same position when viewed from the optical
axis direction. Accordingly, the arrangement of the first lenses 22 is as
shown in FIG. 4. That is, a pitch p between centers of the first lenses
22 and a shift size d between the first lenses 22 are the same as those
of the optical-fiber insertion holes 25.

[0081]The second lenses 33 of the optical module 3, and the light-emitting
device and the light-receiving device constituting the light input and
output end 41 are disposed at positions consistent with the positions of
the first lenses 25 in plane view of these. The second lenses 33 and the
light input and output ends 41 are arranged two-dimensionally to form a
plurality of rows. Pitches and shift sizes of the second lenses 33 and
the light input and output ends 41 are the same as those of the
optical-fiber insertion holes 25 and the first lenses 25.

[0082]When the holding member body 2 of the present embodiment is
assembled with the front end of the multi-core optical fiber 6, a coating
is removed from the front end portion of the multi-core optical fiber 6
to expose the individual optical fibers 61. The multi-core optical fiber
6 is then inserted from the rear of the holding member body 2. In this
case, the multi-core optical fiber 6 is then inserted so that the front
end of the optical fiber 61 contacts the bottom portion 250 of the
optical-fiber insertion hole 25, such that the front end of the optical
fiber 61 and first lens 25 are positioned. The multi-core optical fiber 6
is bonded to the holding member body 2 using, for example, adhesive.

[0083]When the multi-core optical fiber 6 assembled into the holding
member body 2 is optically connected to the light input and output end 41
mounted on the optical module 3, the mounting surface 28 of the first
holding member body 2 is caused to oppose the bonding surface 31 of the
optical module 3, as shown in FIG. 6. The positioning pins 29 protruding
from the mounting surface 28 of the holding member body 2 are then
inserted into the positioning pin holes 39 formed in the bonding surface
31 of the optical module 3, such that the holding member body 2 is
engaged with the optical module 3. In this case, the front end of the
holding member body 2 is brought into contact with the guide portion 52
of the lens holder 5, such that the positioning can be easily performed.
Accordingly, the multi-core optical fiber 6 arranged to face the
reflective surface 21 is correctly positioned with respect to the light
input and output end 41, and the multi-core optical fiber 6 is optically
connected to the light-emitting device 42 or the light-receiving device
43 through the reflective surface 21.

[0084]The first lenses 22 and the second lenses 33 are provided on the
optical path between the multi-core optical fiber 6 and the light input
and output end 41. Accordingly, light output from the multi-core optical
fiber 6 is reflected by the first lens 22 to be a light beam vertical to
the optical axis direction of the multi-core optical fiber 6, and the
light beam is focused by the second lens 33 and incident to the
light-receiving device 43. Alternatively, light output from the
light-emitting device 42 is converted to be a light beam parallel to the
optical axis of the light input and output end 41 through the second lens
33, and the light beam is reflected and focused by the first lens 22 and
incident to the front end of the optical fiber 61.

[0085]The optical path change member 1 of the present embodiment has the
first lenses 22 having a lens shape provided on the reflective surface
21, such that the optical path can be maintained in a desired direction
even when the direction of the incident light is shifted.

[0086]Further, the optical-fiber insertion hole 25 for precisely
positioning the multi-core optical fibers 6 and the reflective surface 21
are formed in the holding member body 2, which is an integral part and
has a block shape, and a position relationship between the optical axis
direction of the optical fiber 61 and the reflective surface 21 is
accurately fixed. Accordingly, each optical fiber 61 and each light input
and output end 41 precisely correspond to each other.

[0087]Accordingly, even when the multi-core optical fibers 6 are arranged
two-dimensionally, the optical path is accurately changed on the
reflective surface 21. Further, an overall structure of an optical
connector can be miniaturized.

[0088]The multi-core optical fibers 6 arranged in a plurality of rows
realize a much higher density than a plurality of optical fibers aligned
in a row.

[0089]As shown in FIG. 3, the arrangement of the optical-fiber insertion
holes 25 is a staggered arrangement in which a plurality of rows 25A and
25B of a plurality of optical-fiber insertion holes 25 arranged side by
side are fowled and the positions of the optical-fiber insertion holes 25
are shifted from each other between the first row 25A and the second row
25B. Accordingly, an interval between the end faces of the optical fibers
61 positioned by the optical-fiber insertion holes 25 is broadened.
Accordingly, interference of noise or signal light due to a beam spread
to the optical paths of the adjacent optical fibers 61 is prevented. As a
result, it is possible to realize an excellent optical connection.

[0090]In the light input and output ends 41 provided in two rows in the
longitudinal direction, the light-emitting devices 42 are provided in a
row at a front side and the light-receiving devices 43 are provided in a
row at a rear side. Therefore, the first row of the two rows of
multi-core optical fibers 6 can be used for reception only and the second
row can be used for transmission only, thereby obtaining a high-density
multi-channel optical transceiver capable of preventing crosstalk.

[0091]Further, since the second lenses 33 are provided on the optical path
between the first lenses 22 and the light input and output ends 41, it is
possible to maintain the optical path in a desired direction even when
the direction of the incident light between the first lens 22 and the
light input and output end 41 is shifted.

[0092]While in the arrangement of the light input and output ends 41
according to the present embodiment, the light-emitting devices 42 in the
light input and output ends 41 provided in the two rows in the
longitudinal direction are provided in a row at a front side and the
light-receiving devices 43 are provided in a row at a rear side, the
present invention is not limited thereto. The light-emitting devices 42
and the light-receiving devices 43 may be rearranged depending on
specifications.

Second Embodiment

[0093]Hereinafter, a second embodiment of the present invention will be
described.

[0094]While in the embodiment shown in FIGS. 3 and 4, the optical-fiber
insertion holes 25 and the first lenses 22 are arranged in two rows, the
optical-fiber insertion holes 25 and the first lenses 22 may be arranged
in three or more rows according to the present invention.

[0095]When the optical-fiber insertion holes 25 are arranged in three or
more rows, the positions of the optical-fiber insertion holes 25 are
shifted from each other at least between adjacent ones of the rows.
Accordingly, an interval between the optical fiber of the upper row and
the optical fiber of the lower row is broadened, and thus, interference
of noise or signal light can be prevented for an excellent optical
connection.

[0096]FIG. 5 is a cross-sectional view of the holding member body 2 in
which first lenses 22a are arranged in three rows as the multi-core
optical fibers 6 are configured in three rows according to the second
embodiment. For convenience, in the following description of the second
embodiment, the rows are indicated as a first row 22A, a second row 22B,
and a third row 22C in order from the shortest to the largest distance
from a mounting surface 28.

[0097]In the holding member body 2 of the second embodiment shown in FIG.
5, the positions of the first lenses 22a are shifted in a lateral
direction of the holding member body 2 (a horizontal direction in FIG.
5), at least, between the first row 22A and the second row 22B and
between the second row 22B and the third row 22C. It is preferable that
the positions of the first lenses 22a are also shifted from each other in
the lateral direction of the holding member body 2 even between the first
row 22A and the third row 22C that are not adjacent to each other.

[0098]Shift sizes d1, d2 and d3 are greater than beam diameters of optical
paths so that the optical paths do not overlap. In FIG. 5, d1 denotes a
shift amount between the second row 22B and the third row 22C, d2 denotes
a shift amount between the second row 22B and the first row 22A, and d3
denotes a shift amount between the third row 22C and the first row 22A.
The shift amounts d1, d2 and d3 may be the same. Alternatively, two of
d1, d2 and d3 may be the same or all of them may be different. As shown
in FIG. 5, the first lenses 22a belonging to the same row 22A, 22B or 22C
and adjacent to each other are arranged at regular intervals so that
pitches p between centers of the first lenses 22a are the same. In this
case, since a relationship of d1+d2+d3=p is satisfied, the pitch p is
intended to secure the shift amounts d1, d2, and d3 between the rows 22A,
22B and 22C. A minimum value of the shift amounts d1, d2 and d3 may be
smaller than p/3 as long as the foregoing is satisfied.

[0099]When the number of rows of the optical-fiber insertion holes 25 is
4, 5 or, the like, the arrangement of the optical-fiber insertion holes
25 may be determined based on the foregoing.

Third Embodiment

[0100]Hereinafter, a third embodiment of the present invention will be
described.

[0101]FIG. 7 is a cross-sectional view showing an optical path change
member 1A in which first lenses are not formed on a reflective surface
21A. The optical path change member 1A has the same configuration as the
optical path change member 1 shown in FIG. 1 except that the first lenses
are not formed on the reflective surface 21A of a holding member body 2.

[0103]It is preferable that since parallelization of light by the first
lenses is not performed in the optical path change member 1A, the optical
paths 30 of optical fibers 61 have the same length to prevent beam
diameters of lights of the optical, fibers 61 from being non-uniform. For
example, it is preferable that optical paths 30A and 30B of optical
fibers 61A and 61B inserted into the optical-fiber insertion holes 25 of
different rows 25A and 25B (see FIG. 7) have the same lengths.

[0104]Even when the lengths of the optical paths are not the same, there
is no problem when light is parallelized by adjusting, for example,
profiles of the second lenses of a lens holder. For example, in the
example shown in FIG. 7, even though the lengths of the optical paths 30A
and 30B of the optical fibers 61A and 61B in the different rows 25A and
25B are not the same, the non-uniformity of the beam diameters is not
caused as long as the profiles of the second lenses 33 of the lens holder
5 (e.g., the curvatures of the second lenses 33) (see FIG. 1) are set so
that the light can be parallelized.

[0105]In the optical path change member 1A, the optical-fiber insertion
holes 25 for precisely positioning the two-dimensionally arranged
multi-core optical fibers 6, and the reflective surface 21A are formed in
the holding member body 2, which is an integral part and has a block
shape, similarly with the optical path change member 1 of the first
embodiment described above.

[0106]Accordingly, a position relationship between the optical axis
direction of the optical fiber 61 and the reflective surface 21A is
accurately determined and each optical fiber 61 and each light input and
output end 41 precisely correspond to each other.

[0107]Thus, even when the multi-core optical fibers 6 are
two-dimensionally arranged, the optical path is accurately changed on the
reflective surface 21A.

[0108]Further, since the optical-fiber insertion holes 25 and the
reflective surface 21A are formed in the holding member body 2, which is
an integral part and has a block shape, the overall structure can be
miniaturized.

[0109]Since the first lenses are not formed on the reflective surface 21A,
the structure of the optical path change member 1A is simple and a
structure of a mold for molding the holding member body 2 is simplified.
Thus, the optical path change member 1A can be manufactured at a low
cost.

[0110]While the preferred embodiments of the present invention have been
described, the present invention is not limited to the embodiments.
Additions, omissions, substitutions, and other variations may be made to
the present invention without departing from the scope of the present
invention. The present invention is not limited by the above description,
but only by the appended claims.